Re: IMS bugs and proposals

From: Christian Balzer <>
Date: Wed, 9 Oct 1996 09:14:18 +0200 (MET DST)

Earl Fogel wrote:
>On Mon, 7 Oct 1996 Christian Balzer <> wrote:
>>However people who think that the latest Dilbert strip has
>>to be out now can and will hit the "Reload" button, a lot. Right now
>>I estimate that about 20-30% of the external accesses are TCP_REFRESH
>>requests of perfectly valid data. An option to Squid which allows
>>these requests to be transformed into an IMS/size check procedure would
>>greatly reduce this load.
>Yes, please.
>Also, when you hit Reload, Netscape includes a Pragma: no-cache HTTP header
>in the request, and squid doesn't service the request from it's cache. I'd
>think that's the correct behavior for GET requests, but when a request
>includes both an LMS and a Pragma: no-cache, *and* squid has a cached copy
>of the document that's newer than the one the browser has, then I think
>squid should return it's cached copy.
>So, hitting Reload would always give you a newer copy of a document
>(if one is available), but it wouldn't necessarily give you the newest
Well, if somebody did hit Reload it's only fair to check at the source (but
using IMS/size check if possible and not transfering everything again),
once a cache is trusted by the users to be current enough by itself the
reloads will drop...

>>Incidently I do see some TCP_IMS_HIT in the
>>access logs, so some browsers must be doing things more sensible
>>than Netscape (or am I missing something obvious here?).]
>I've been told that MSIE does not include the Pragma: no-cache header
>on Reloads.
True, in an ideal world Netscape would use a complete IMS check on
simple reload and the no-cache header on shift-Reload...

Mata ne,


  // <CB> aka Christian Balzer, Tannenstr. 23c, D-64342 Seeheim, Germany
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Received on Wed Oct 09 1996 - 00:17:13 MDT

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